Control apparatus



' F65; v. D. BARKER 2,190,820

coN'rnoL. APPARATUS Filed m. 11, 1936 2 Shuta-Shegt 1 0 Yo fl". I ,1:

' INVENTOR u a. sun-n ATTORNEY Feb. 20, 1940.

v. D. BARKER com-1 01. APPARATUS Filed Feb. 11, 193$ 2 Shoots-Sheet 2 Rr i I n R w. u G G m E Y m m M n Q/\ P n N w A A 0 k 0 u N W w s .wwrwWW 5 Nu 4 y T 8 o F I W I v E n 3 h II n on N r k 3 I. w r k E 3 mum u.4 R n llll q Q m 6E Patented Feb. 20, 1940 UNITED STATES PATENT orrlcsCONTROL APPARATUS Application February 11, 1936, Serial No. 63,456

11 Claims.

This invention relates to control apparatus and more particularly toapparatus for controlling the power current in electrical weldingapparatus.

In electrical welding apparatus and especially in electrical-spotwelding machines it is important to be able to control in an accurateand adjustable manner, the time period during which welding current issupplied to the welding electrodes while in operation.

An object of the present invention is to provide a simple,'reliable,adjustable and accurately operating apparatus to close an electriccircuit for an adjustably predetermined period of time.

In one embodiment of the invention a welding machine has a pair ofresiliently mounted independently movable contacts to close and open thepower circuit, the two contacts being held open, allowed to close,forced open, and reset in their original positions by a pair ofrotatable actuating members driven by a one revolution clutch from auniformly rotating shaft, the twoactuating members being adjustablerelatively to each other to vary the several time periods involved inone cycle of operation.

Other objects and features of the invention will appear from thefollowing detailed description of one embodiment thereof taken inconnection with the accompanying drawings in which the same referencenumerals are applied to identical parts in the several figures and inwhich- Fig. l is a partly diagrammatic broken view in side elevation ofa welding machine embodying the invention;

Fig. 2 is a detached plan view of the clutch member and associatedparts;

Fig; 3 is a view on the broken line 33 of Fig.

Fig. 4 is a partial view in rear elevation of the adjustment collar;

Fig. 5 is a broken view partly in longitudinal vertical section of thecontrol mechanism proper;

Fig. 6 is a broken view thereof in front elevation, and

Fig. '1 is a detached view in perspective of the f detent is laterallyoffset and covers only a porcontrel contacts and associated parts.

In the embodiment herein disclosed, a spot welding machine generallyindicated at I6 is mounted on a bench, bracket or other .suitablesupport having a table member 20. The welder proper has a base 2| onwhich is mounted a stationary electrode 22. A movable coacting electrode23 is carried by a pivotable arm 24 mounted on the base 2!. Weldingcurrent is fed to the electrodes 22 and 23 by cables 25 and 26 from thesecondary winding of a step down transformer not shown. The arm 24 isheld up and the electrode 23 out of contact with the electrode 22 by ahelical compression spring 21. When it is desired to bring theelectrodes together, the treadle 28 is depressed from the dotted to thefull line position shown in Fig. 1. This draws the pull rod 29 down,which in turn depresses the lever arm 3|] through the adjustablecompression spring 3|. The lever 30 rotates the circular cam 32 in whichis inset the cam member 33 which takes into a corresponding cam notch 34in the pivotable arm 24 and rotates the arm to bring the electrode 23down toward the electrode 22 and against work not shown resting on thelatter.

It is desired that during each approximation of the electrodeselectrical welding current be supplied to them for one and only oneperiod of time of adjustably predetermined length. To this end a controlmechanism generally indicated at 19 is associated with the welder [8. Inthe control device 19 there is a pair of coacting contacts 35 and 36connected by leads 31 and 38 in the primary circuit of the step downtransformer not shown whose secondary is connected to the electrodes 22and 23 by the cables 25 and 26, so that while the contacts 35 and 36 areabutted together, the primary circuit is closed and welding current isfed by the secondary to the electrodes 22 and 23.

' The contact 35 is mounted in the downwardly extending arm 39 of a'bellcrank lever pivoted on a stub shaft 40 rigidly mounted in the frame ofthe mechanism. The contact 36 is mounted in the downwardly extending armH of a second bell crank lever pivoted on the same stub shaft,

the arm 39 and the arm 41 being laterally offset in opposite directionsto bring the contactsinto the same plane of rotation about the shaft.The

horizontal arms 42 and 43 respectively belonging to the arms 39 and 4|extend horizontally from the shaft to the left (Fig. 6) side by side.The outer end of the arm 42 is notched to coact with a detent 44pivotably mounted on a stub 45 carried on the machine frame. The head 46of the tion of the width of the arm 42 at the outer side of the arm andextends outwardly beyond the same.

A bracket 46 is formed on the machine frame and serves as a commonabutment for the lower ends of two compression springs 41 and 43 whoseupper ends bear respectively against the under faces of the arms 42 and43. That portion 49 of the machine frame which carries the stubs 49 and46 and the bracket 46 is adjustable on the control mechanism base 56 bymeans of opposed clamp screws 5i and 52. The two bell crank levers 33,42 and 4|, 43 have third arms 62 and 63, and a stop member 64 is mountedon thd movable part of the frame. Thus this latter may be rea by asynchronous electric motor also not shown.

, 16 in the periphery of a An adjustable timing collar 58 is rotatablymounted on a forwardly extending reduced portion of the cain 54 and heldthereon by the collar 51. The collar 58 is yieldably held againstrotation on the cam 54 by means of a spring pressed cone pointed detent59. mountedin the cam and coacting with an annularly positioned sequenceof radially disposed notches formed on the rear face of the collar 58.The contact surface of the rear face of the collar 58 with the cam 54 issubstantially in the plane of the front face of the arm 42. A screwhaving a head 6| is mounted in the cylindrical outer surface of thecollar 56 so that the head 6| projects radially outwardly from thecollar so as to contact with and trip the detent 46 when carried down toand past the same. I

The rear end of the cam 54 is formed with clutch teeth and a set ofcoacting teeth is formed on the forward'end of a clutch member 66mounted on the shaft 55 to be longitudinally slidable thereon, butkeyedthereto by keys 61 to rotate therewith. The clutch member 66 is slid onthe shaft by means of twin lever arms 63 pivoted inbrackets on themachine frame by means of a shaft 69 passing through a body I0 integralwith the arms 68. A downwardiyextending arm II also integral with thebody is constantly urged forward by a compression spring 12 thus tendingto keep the clutch member 66 out of engagement with the cam 54. Anotherforwardly extending arm 13 also integral with the body 13 is formed atits outer end with an upwardly directed nose 14 which enters acorresponding notch portion of the cam 54.

A pullrod 16 attached at its lower-end to the treadle 28, passes upthrough a guide hole in the base 50 and is formed at'its upper end witha hook or detent 11 capable of hooking over the arm 13 to pull the samedown. The upper portion of the pullrod 161s resilient to permit thedetent 11 to be pushed oil the arm 13 by a pin I6 mounted in the cam 54.i

In operation, the motor driving the shaft 55 when the treadle hasadvanced a little further (how far depending upon the adjustment oftendon of the spring 3|) the pullrod'E will release the nose 14 fromthe'notch I5 by'pulling down the lever arm 13 against the spring I2. Atthe same time the arms 63 will move the clutch member 66 to engage thecam 54 and start the same to rotating in the direction of the arrow inFigs. 3 and 6. This rotation will continue until the pin 13 has madenearly one revolution with the cam 54 and strikes the right side of thedetent 11 (Fig. 3) dislodging the detent from the lever arm 13. Thelatter at once files up under the drive of the spring 12, the nose 14enters the notch 15, and the cam is thus stopped after one revolution.This is possible because, as the arm 13 rises, the arms 68 are alsomoved to shift and.

hold the'clutch member 66 out of engagement with the cam 54.

When the cam 54 begins to revolve (which'is not until after theelectrode 23 has been applied to the work) the cam nos'ei leaves thearms 42 and 43. The arm 42 is hel in place against the drive of itsspring 41 by the detent 46, but the arm 43 is driven up by the spring46. This action swings the contact 36 on the arm 4| to the left intocontact' with the contact 35, which closes the primary circuit of thewelding transformer through the leads 3'! and 36 and causes thesecondary winding of the transformer to begin delivering current to theelectrodes 22 and 23 through the cables 25 and 26. The lever 43, 4| isheld in this position by the pressure of contact 36 against contact 35,and the arm 63 is then very nearly down on the stop 64 while the top ofthe arm 43 is out of contact with the cam 54. This state of affairscontinues until the screw head 6| is carried around by the cam andpushes the detent 4601f the arm 42.

Immediately the arm 42 flies up under the drive of the spring 41, thearm 39 carries the contact 35 abruptly away from the contact 36 and thearms 62*and 63 come down on and stop against the stop member 64. Thesupply of current to the transformer primary is thus broken at 35, 36and hence the welding current also ceases.

Later the cam nose 53 returns the levers 39, 42, 62 and 4!, 43, 63 totheir first positions just as the nose 14 stops the revolution of thecam.

The clutch 66 will not be again engaged with the cam 54 until thepullrod 16 has been permitted to rise to allow its resiliently flexibleupper end to reset the hook 11 over the lever arm 13. Each depression ofthe treadle will occasion one and only one approximation of theelectrodes and during this will effect one and only one revolution ofthe cam 54 and therefore one and only one application of welding currentto the electrodes.

The length of the timeof closure of the welding circuit depends upon therotary speed of the shaft 55 and upon the peripheral distance around thecam 54 and the collar 58 from thecam nose 53 to the screw headlil, forwhen the .nose releases the arm 43 the welding circuit is closed untilthe screw head strikes the detent 46 and releases the arm 42. Thedistance between the cam nose and the screw head can be adjusted byturningthe sleeve 56, which carries the screw head, manually on the cam54 which carries the cam nose, the resilient detent 53 'yielding5t0allowiof such adjustment but holding the parts relatively immovable inoperation. This adjustment has an angular range about the common axis ofthe parts from a minimum of 6 to a maximum of 342 by steps of 6 in thestructure shown where the adjustment notches I are 6' apart. Thisrepresents a minimum of one sixtieth and a maximum of fifty sevensixtieths of a revolution of parts M and In one instance in practice theshaft 55 was driven by a synchronous motor at 30 R. P. M. The weldingcurrent period, therefore, could be adiusted by steps of two cyclesfroma minimum of two cycles to a maximum of 114 cycles of 60 cycle current;4

The invention is disclosed herein as embodied in a timing device for awelding machine but is not limited to such application but is obviouslyof use wherever it is desired to close an electrical circuit for anaccurately predeterminable and adi fi i ble period of time. Theembodiment herein disclosed is illustrative only and may be 4 widelymodified and departed from in many ways without departing from thespirit and scope of the invention as pointed out in and limited only bythe appended claims.

What is claimed is: 1 1. A control device to close an electric circuitfor a predeterminable interval of time compris-' ing a first springpressed rotary member having a contact member thereon' and tending torotate from one position to another position, a second spring pressedrotary member having a contact member thereon and tending to'rotate fromone position to another position, a detent to hold the second rotarymember releasably in the first position thereof, and a rotatable memberactuable at will for one cycle of operation only and having a camthereon to move both rotary members from their second positions to theirfirst positions and to hold the first rotary member releasably in thefirst position thereof and having releasing means thereon to release thesecond rotary member from the detent, the contact member on the firstrotary member being in contact with the contact member on the. secondrotary member only when the first rotary member is in its secondposition and the second rotary member is in its first position.

2. A control device to close an electric circuit for a predeterminableinterval of time comprising a first spring pressed rotary member havinga contact member thereon and tending to rotate from one position toanother position, a second spring pressed rotary member having a contactmember thereon and tending to rotate from one position to anotherposition, a detent to hold the second rotary member. releasably in thefirst position thereof, a rotatable member actuable at will for onecycle of operation only and having a cam thereon to move both rotarymembers from their second positions to their first positions and to holdthe first rotary member releasably in the first position thereof andhaving releasing means thereon to release the second rotary member fromthe detent, the contact member on the first rotary member being incontact with the contact member on the second rotary member only whenthe first rotary member is in its second position and the second rotarymember is in its first position, and constant speed means to drive therotatable member.

3. A control, device toclose an electric circuit for a predeterminableinterval of time comprising a first spring pressed rotary member havinga contact member thereon and tending to rotate from one position toanother position, a second spring pressedrotarymember having a contactmember thereon and tending to rotate from one position to anotherposition, a detent to hold the second rotary member releasably in thefirst one position to another position,

contact with the contact member on the second rotary member only whenthe first rotary member is in its second position and the second rotarymember is in its first position, constant speed means, and means tocouple the constant speed means to the rotatable member at will to drivethe rotatable member for one rotation thereof only.

4. -A controldevice to close an electric circuit for a predeterminablein al of time comprising a first spring pressed r0 7 ry member having acontact member thereon an tending to rotate from one position to anothersition', a second spring pressed rotary member having a contact memberthereon and tie ding to rotate from one position to another posit on, adetent to hold the second rotary member, releasably in the firstposition thereof, a rotatable member having a cam thereon'to move bothrotary members from their second positions to their first positions andto hold the first rotary member releasably in the first position thereofand having releasing means thereon to release the second rotary memberfrom the detent, the contact member on' the first rotary member being incontact with the contact member on the second rotary member only whenthe first rotary member is in its second position and the second rotarymember is in its first position, and means to drive the rotatable memberat will for one rotation thereof only at predetermined speed.

5. A control device to close an electric circuit for a predeterminableinterval of time comprising a first spring pressed rotary'member havinga contact member thereon and tending to rotate from one position toanother position, a second spring pressed rotary member having acontact, 5

tions and to hold the first rotary member releasably in the firstposition thereof and haying releasing means thereon to release thesecond rotary member from the detent, the contact member on the firstrotary member being in contact with the contact member on the secondrotary member only when the first rotary mem-, ber is in its secondposition and the second rotary member is in its first position, andmeans to drive the movable member at will for one i cycle of movementthereof only at predetermined 6. control device to close an electriccircuit for a predetermlnable interval of time comprising a first springpressed shii'table member hav- 1' ing a contact thereon and tending toshift from pressed shiftable member having a contact thereon and tendingto shift from one position to another position, a detent to hold thesecond shiftable member in-the first position thereof, a

I movable member having means thereon to move both shiftable membersfrom their secondposi-' tions to their first positions and to hold thefirst a second means to drive the movable member at will for one cycleof movement thereof only at predetermined speed.

7. A control device to close an electric circuit for a predeterminableinterval of time comprising a first contact member tending to shift fromone position to another position, a second contact member tending toshift from one position to another position, means to releasably holdthe second contact member in its first position, a movable member havingmeans thereon to move both shiftable members from their second positionsto their first positions and to hold the first shiftable memberreleasably in the first position thereof and having releasing meansthereon to release the second shiftable member from the holding means,the two contact members being in contact with each other only when thefirst contact member is in its second position and the second contactmember is in its first position, constant'speed means, and means tocouple the movable member at will to the con-- stant speed means todrive-the movable member for one cycle of movement only.

8. A control device to close an electric circuit for a predeterminableinterval oi time comprising a first contact member tending to shift fromone position-to another position, a second contact member tending toshift from one position to another position, means to releasably holdthe second contact member in its first position,

a movable member having means thereon to move both shiftable membersfrom their second positions to their first positions and to hold thefirst shiftable me'mberreleasably in the first position thereof andhaving releasing means thereon to. release the second shiftable memberfrom the holding means, thetwo contact members being in contactwith'each other only when the first contact member is in its secondposition and the second contact member is in its first position, andmeans to drive the movable member at will for onetcycle of movement onlyat predetermined speed.

9. A control device to close an electric circuit for a predeterminableinterval of time comprising coaxially movable contact members havingprojections, resilient means for urging each contact member in onedirection, constant speed means, a contact control element positioned toengage the projections to hold the contact members in spaced positionsagainst the force of their resilient means, means for operativelyconshiftable member releasably in the first position necting the elementto the constant speed means to cause movement of the element to releasethe contact members, auxiliary means to hold one of the contact membersagainst movement while the first released contact member is urged intoengagement therewith by its resilient means,

and means adjustable relative to the element and movable therewith toactuate the auxiliary means to render effective the resilient means ofthe second contact member to urge said member away from the firstreleased contact member.

10. A control device to closean electric circuit for a predeterminableinterval of time comprising coaxially movable contact members havingprojections, resilient means for ,urging each contact member in onedirection, constant speed means, a contactcontrol element positioned toengage the projections to hold the contact members in spaced positionsagainst the force of their resilient means, means for operatively COD-emeeting the element to theconstant speed means to cause movement of theelement to release the contact members, auxiliary means to hold one ofthe contact members against movement while the first released contact,member is urged into.

engagement therewith by its resilient means,

released contact member, and means adjustable 'relative to the elementand movable therewith to actuate the auxiliary means to render effectivethe resilient means of the second contact member to move said memberaway from the first released member by its resilient means. 11. Acontrol device toclose an electric circuit for a predeterminableinterval of time comprismeans for limiting the movement of the first ingcoaxially movable contact members having projections, resilient meansfor, urging each contact member in one direction, constant speed means,acontact control element positioned to engage the projections to normallyhold the contact members in spaced positions against. the force of theirresilient means, means for operatively connecting the element to theconstant 'means, means for limiting the movement of the first releasedcontact member, and means adjustable relative to the element and movabletherewith to actuate the auxiliary means to render effective theresilient means of the second contact member to move said member awayfrom the first released contact member by its resilient means, saidelement being conditioned to return the contact members to their-normalpositions at the termination 'of its movement.

VIRGIL D. BARKER.

